In plants, apical meristems allow continuous growth along the body axis. Within the root apical meristem (RAM), a group of slowly dividing quiescent center (QC) cells is thought to limit stem cell activity to directly neighboring cells (Cowels, 1956; van den Berg et al., 1997), thus endowing them with unique properties, distinct from displaced daughters. This binary identity of the stem cells stands in apparent contradiction with the more gradual changes in cell division potential (Bennett and Scheres, 2010) and differentiation (Yamaguchi et al., 2008; 2010; Furuta et al, 2014; Geldner, 2013; Masucci et al., 1996; Dolan and Costa, 2001) that occur as cells move further away from the QC. To address this paradox and to infer molecular organization of the root meristem, we used a whole-genome approach to determine dominant transcriptional patterns along root ontogeny zones. We found that the prevalent patterns are expressed in two opposing gradients. One is characterized by genes associated with development, the other enriched in differentiation genes. We confirmed these transcript gradients, and demonstrate that these translate to gradients in protein accumulation and gradual changes in cellular properties. We also show that gradients are genetically controlled through multiple pathways. Based on these findings, we propose that cells in the Arabidopsis root meristem gradually transition from 'stemness' towards differentiation. Overall design: This study contains high-resolution datasets from cell populations from the enitre root meristem and xylem-specific cell populations. Using fluorescence activated cell sorting, three cell populations were isolated based on their GFP expression intensity. Two-Three replicates were used per sample
Framework for gradual progression of cell ontogeny in the <i>Arabidopsis</i> root meristem.
Specimen part, Cell line, Subject
View SamplesWOX5 maintains columella stem cells in the Arabidopsis root and prevents their differentiation. In order to understand the molecular mode of WOX5 action the genes differentially expressed by WOX5 inducible over-expression were determined by analysis of microarray hybridizations. Seedlings transformed with a dexamethasone inducible WOX5 construct were induced for one or four hours with dexamethasone or a mock solution. Other seedlings were treated one hour with cycloheximide ( a protein synthesis inhibitor to reduce secondary transcriptional effects after WOX5 activation) and either dexamethasone or a mock solution. Root tips were harvested, RNA extracted, and the RNA samples prepared for hybridization to Affymetrix microarrays. Potential target genes of WOX5 were further analyzed by transcriptional markers, qPCR and EMSA (electrophoretic mobility shift assay).
Organizer-Derived WOX5 Signal Maintains Root Columella Stem Cells through Chromatin-Mediated Repression of CDF4 Expression.
Specimen part, Compound, Time
View SamplesIn order to identify targets of the transcription factor AUXIN RESPONSE FACTOR5 / MONOPTEROS (ARF5/MP), we compared transcriptomes of mp-B4149 mutant seedlings (9 day-old) and seedlings carrying the dexamethasone-inducible version of the MP inhibitor protein BODENLOS (GR-bdl). Without dexamethasone (DEX) treatment, this line is identical to the wild-type, while DEX treatment leads to strong inhibition of ARF-dependent transcription. To remove all endogenous MP-inhibiting Aux/IAA proteins, we treated mp or GR-bdl seedlings during 1 hour with auxin (50 micromolar Indole-3-Acetic Acid), either with or without a pretreatment with 10 micromolar DEX for 1 hour. Genes that are activated by MP are expected to br downregulated in mp seedlings and in the GR-bdl line afer DEX treatment. We used biological duplicates for each of the three treatments.
MONOPTEROS controls embryonic root initiation by regulating a mobile transcription factor.
No sample metadata fields
View SamplesThe murine model of Lyme disease provides a unique opportunity to study the localized host response to similar stimulus, B. burgdorferi, in the joints of mice destined to develop severe arthritis (C3H) or mild disease (C57BL/6). Pathways associated with the response to infection and the development of Lyme arthritis were identified by global gene expression patterns using oligonucleotide microarrays. A robust induction of IFN responsive genes was observed in severely arthritic C3H mice at one week of infection, which was absent from mildly arthritic C57BL/6 mice. In contrast, infected C57BL/6 mice displayed a novel expression profile characterized by genes involved in epidermal differentiation and wound repair, which were decreased in the joints of C3H mice. These expression patterns were associated with disease state rather than inherent differences between C3H and C57BL/6 mice, as C57BL/6-IL10-/- mice infected with B. burgdorferi develop more severe arthritis that C57BL/6 mice and displayed an early gene expression profile similar to C3H mice. Gene expression profiles at two and four weeks post infection revealed a common response of all strains that was likely to be important for the host defense to B. burgdorferi and mediated by NF-kB-dependent signaling. The gene expression profiles identified in this study add to the current understanding of the host response to B. burgdorferi and identify two novel pathways that may be involved in regulating the severity of Lyme arthritis.
Gene expression profiling reveals unique pathways associated with differential severity of lyme arthritis.
No sample metadata fields
View SamplesLand plants can reproduce sexually by developing an embryo from a fertilized egg cell. However, embryos can also be formed from other cell types in many plant species. A key question is thus how embryo identity in plants is controlled, and how this process is modified during non-zygotic embryogenesis. The Arabidopsis zygote divides to produce an embryonic lineage and an extra-embryonic suspensor. Yet, normally quiescent suspensor cells can develop a second embryo when the initial embryo is damaged, or when response to the signaling molecule auxin is locally blocked. Here we have used auxin-dependent suspensor embryogenesis as a model to determine transcriptome changes during embryonic reprogramming. We find that reprogramming is complex and accompanied by large transcriptomic changes prior to anatomic changes. This analysis revealed a strong enrichment for genes encoding components of auxin homeostasis and response among misregulated genes. Strikingly, deregulation among multiple auxin-related gene families converged upon re-establishment of cellular auxin levels or response. This suggests a remarkable degree of feedback regulation to create resilience in auxin response during embryo development. Starting from the transcriptome of auxin-deregulated embryos, we identify an auxin-dependent bHLH transcription factor network that mediates the activity of this hormone in suppressing embryo development from the suspensor.
A Robust Auxin Response Network Controls Embryo and Suspensor Development through a Basic Helix Loop Helix Transcriptional Module.
Specimen part
View SamplesWe isolated QC and xylem cells by sorting GFP+ cells marked with pWOX5::GFP and pTMO5::GFP respectively.
Predicting gene regulatory networks by combining spatial and temporal gene expression data in <i>Arabidopsis</i> root stem cells.
Specimen part
View SamplesSuperSeries contain expression data from the nuclei of cell types involved in patterning events, with focus on root apical stem cell formation, at 16-cell stage, early globular stage and late globular stage in the early Arabidopsis embryo (atlas). Expression data comparing nuclear and cellular RNA isolated from whole 16-cell stage Arabidopsis embryos is also included.
Transcriptome dynamics revealed by a gene expression atlas of the early Arabidopsis embryo.
Specimen part
View SamplesThe establishement of the first plant tissues occurs during embryo development. Indeed, cell types that will form the Arabidopsis root stem cell niche are first specified during 16-cell (16C), early globular (EG) and late globular (LG) stage of embryonic development. While some regulatory factors are known, we do not yet understand the genetic networks underlying the specification of these cell types. One main reason for this is the difficulties in adapting genome-wide approaches to the cellular level. Here, we have adapted such an approach (INTACT) to generate microarray-based cell type-specific transcriptomic profiles at 16C to LG stage for use in determining the role of the transcriptome in cell specification and differentiation during root stem cell niche formation.
Transcriptome dynamics revealed by a gene expression atlas of the early Arabidopsis embryo.
Specimen part
View SamplesGene expression profile of joint tissue from C3H and interval specific congenic mouse lines (ISCL) following infection with Borrelia burgdorferi
Interval-specific congenic lines reveal quantitative trait Loci with penetrant lyme arthritis phenotypes on chromosomes 5, 11, and 12.
Specimen part
View SamplesT lymphocytes are essential contributors to the adaptive immune system and consist of multiple lineages that serve various effector and regulatory roles. As such, precise control of gene expression is essential to the proper development and function of these cells. Previously, we identified Snai2 and Snai3 as being essential regulators of immune tolerance partly due to the impaired function of CD4+ regulatory T cells in Snai2/3 conditional double knockout mice. Here we extend those previous findings using a bone marrow transplantation model to provide an environmentally unbiased view of the molecular changes imparted onto various T lymphocyte populations once Snai2 and Snai3 are deleted. The data presented here demonstrate that Snai2 and Snai3 transcriptionally regulate the cellular fitness and functionality of not only CD4+ regulatory T cells but effector CD8a+ and CD4+ conventional T cells as well. This is achieved through the modulation of gene sets unique to each cell type and includes transcriptional targets relevant to the survival and function of each T cell lineage. As such, Snai2 and Snai3 are essential regulators of T cell immunobiology. Overall design: GFP- CD3e+ CD8a+ CD4-, GFP- CD3e+ CD8a- CD4+ CD25- and GFP- CD3e+ CD8a- CD4+ CD25+ T cells were isolated from spleens of UBC-GFP mice transplanted with WT or cDKO lineage-depleted donor bone marrow following lethal irradiation of recipient mice. RNA-seq was performed on 3-4 biological replicates from each genotype for all T cell populations analyzed.
Snai2 and Snai3 transcriptionally regulate cellular fitness and functionality of T cell lineages through distinct gene programs.
Specimen part, Cell line, Subject
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